1. Field of the Invention
The present invention generally relates to hinge mechanisms, and more particularly to a hinge mechanism for hinging together the housings of a foldable, portable electronic device such as a foldable radiotelephone.
2. Related Art
Portable radiotelephones generally have two housings joined by a type of hinge that allows the housings to fold upon one another. Many such foldable radiotelephones have most of the electronics in one housing, called the main housing, and fewer electronics in the other housing, called the cover. Other such foldable radiotelephones have all the electronics in the main housing, with the cover serving only to cover a keypad and a display of the main housing. The main housing and the cover are connected together by a hinge mechanism. The opening or closing of most covers is achieved by means of cams of the hinge mechanism.
One such kind of hinge mechanism is disclosed in China Pat. No. 98109390.6 issued to Kato Electric & Machinery Company. The hinge mechanism comprises a shaft with a flange, a spring, a cam with a hole therethrough, and a sliding cam with a hole therethrough. The cam is fixed to the shaft, while the sliding cam is rotatably assembled on the shaft opposite to the cam. The cam and the sliding cam can slide on the shaft. The spring surrounds the shaft. The sliding cam is fixed to the cover of a portable radiotelephone, while the cam is fixed to the main housing of the portable radiotelephone. When the cover is manually opened, the sliding cam rotates together with the cover. Simultaneously, the spring is pressed as a convexity of the sliding cam rides along a convexity of the cam. Once the cover is opened to a given angle, the cover can continue to open automatically by action of the spring and the convexities. The process of closing the cover is substantially the reverse of the above-described opening process.
However, the convexities are difficult to manufacture. In addition, extra space in the housing and the cover is required for the hinge mechanism. This makes manufacturing of the housing and the cover difficult.
What is need, therefore, is a hinge mechanism which is relatively simple and easy to manufacture.